1. Field of the Invention
This invention pertains to the field of r.f. detectors and more particularly to r.f. detectors having a fin line construction that provides a high degree of isolation between an r.f. input signal and the resulting detected output signal.
2. Description of the Prior Art
In many applications, it is necessary to be able to provide a detected output signal corresponding to an r.f. input signal. For microwave transmissions in general, including those occurring at millimeter wave frequencies, such detection is often accomplished using a detector in microwave circuitry that combines waveguides and coaxial cables. Such combinations are generally costly, difficult to manufacture, and bulky in size. Furthermore, mating such systems to microwave integrated circuits, and printed transmission lines such as microstrip or strip line transmission lines is ordinarily difficult and expensive. On the other hand, printed transmission lines tend to be light in weight, less costly to produce than traditional coaxial and waveguide combinations, and have found increasing use where such characteristics are desirable. Printed transmission lines may however exhibit high loss at high frequencies, and do not permit simple transitions to conventional waveguides.
Fin line transmission lines generally comprise two or more separated conductors positioned on a dielectric substrate and housed within a waveguide. The separated conductors may be deposited on the dielectric substrate or manufactured from clad substrate using a conventional printed circuit techniques. The structure of the fin line type apparatus tends to concentrate the electromagnetic wave in the region of the separation between the conductors. Due to their unique construction, fin line transmission lines combine many of the desirable characteristics of printed transmission lines with those of conventional waveguides while avoiding many of the shortcomings of each.
The principal object of this invention is to provide an improved type of detector having the desirable characteristics of fin line transmission lines including production uniformity, reliability, reduced size, weight, and low cost, as well as excellent compatibility with microwave integrated circuits, printed transmission lines, conventional waveguides and other fin line devices.